Outspoken CFMMEU official John Setka has deleted a social media post that prompted Prime Minister Scott Morrison to threaten the "out of control" union with deregistration.

Mr Setka's contrition about the Twitter post – which showed his two children holding a sign telling the government's Australian Building and Construction Commission to "go get fuc#ed" – came as Opposition Leader Bill Shorten dismissed Mr Morrison's attacks on the CFMMEU as a desperate attempt to distract from the government's internal woes.

Mr Morrison said Mr Setka's post, published on Father's Day, was "the straw that breaks the camel's back" after many years of the union "demonstrating lawlessness and their thuggery, their brutality, their threats".

The Prime Minister said he and Industrial Relations Minister Kelly O'Dwyer would consider legislative and regulatory options for eliminating the militant union, which has paid more than $15 million in fines since 2005. About 80 officials from the union, previously known as the CFMEU until a recent merger with the maritime union, are facing courts on a range of charges.

Advertisement

"The CFMEU has behaved under John Setka like a bunch of thugs, and to involve his children in that, I think, is one of the ugliest things I’ve seen," Mr Morrison said, calling on Mr Shorten to cut Labor ties to the union.

"Mea culpa," Mr Setka said on Monday. "Was emotional on Father’s Day after tough year on family. Shouldn’t have included kids. Now deleted."

Mr Shorten, who relies on factional support from the CFMMEU, said Mr Setka's post was "inappropriate" but defended the union movement and suggested the Prime Minister's comment was overblown.

CFMMEU official John Setka.Credit:Justin McManus

"I'd like to see Prime Minister Morrison more worried about energy prices than he is about tweets from union officials," he said.

"I wish he was as passionate about lifting penalty rates, I wish he was as passionate about protecting Australian jobs as he is about worrying about what's said on social media."

Mr Shorten has come under intense pressure from both the Coalition and inside the Labor Party over his relationship with the union, which boasts over 100,000 members nationally across the construction, forestry, maritime, mining and energy sectors.

Dave Noonan, national construction secretary of the CFMMEU, hit back at Mr Morrison's threats, saying it was "disappointing but not surprising that a broken and divided government is resurrecting the CFMEU bogeyman in an attempt to frighten voters".